Latitude-driven functional trait variations in Zizania latifolia: insights into climate adaptation

Background: Global warming could have a significant impact on plant adaptation to local environments. Widespread species provide a useful model to examine the population dynamic under climate change. However, it is still unclear how widespread aquatic species respond to rapidly changing environments. Wild-rice Zizania latifolia is an emergent macrophyte widely distributed across East Asia. Here, 28 Z. latifolia natural populations covering above 30 latitudes were transplanted in a common garden. Results The growth, photosynthesis and reproduction traits were quantified and compared among populations, and pairwise relationships among geographic, genetic and growth traits were estimated. Results showed that, in the common garden, the high-latitude populations grew in small size indicating weaker competitiveness in warmer temperatures; the low-latitude populations had no sexual reproduction, suggesting that low-latitude individuals stood little chance to migrate successfully to higher latitude. Significantly positive correlations among the distances of genetic, geographic and biological traits for populations indicated that both isolation by distance and isolation by environment models affected the genetic pattern of populations, and phenotypic traits of Z. latifolia populations might be determined genetically. Conclusions All our results suggested that, despite widespread, the genetically determined differentiation of Z. latifolia populations causing growth and reproduction traits could not rapidly acclimate to the accelerated increase of temperature, which implies this widespread species could fail to cope with global warming via migration.